Beginning with the 1997 PM2.5 and Ozone NAAQS, EPA has required the state to submit a demonstration that Oklahoma's State Implementation Plan (SIP) meets the "infrastructure" requirements of CAA Section 110(a)(2)(A)-(M) to implement, maintain, and enforce the National Ambient Air Quality Standards (NAAQS) each time a NAAQS is issued or revised. Recent "Infrastructure SIPs" or "I-SIPs" have been prepared under EPA's September 2013 Guidance on Infrastructure State Implementation Plan (SIP) Elements under Clean Air Act Sections 110(a)(1) and 110(a)(2). A notice providing an opportunity for the public to comment and/or request a public hearing on each proposed I-SIP (beginning with the 2006 24-Hour PM2.5 NAAQS) is posted on AQD's Rules & Planning page. Each I-SIP is then archived on this page once it is finalized and submitted to EPA for review and action.